NFL star Ndamukong Suh, one of the highest-paid defensive players in the league, recently signed a yearlong contract with the Los Angeles Rams for $14 million. Appropriately, when it comes to his finances, Suh has got an all-star mentor: Warren Buffett himself.

Suh's biggest takeaway from working with the icon is simple: Don't be complacent.

"When you look at people who have created great wealth and even Warren Buffett himself, he's made the majority of his money after he was 50," he tells CNBC in the new documentary, "Warren Buffett: Investor. Teacher. Icon." "And we're so young — I think that's where guys gotta understand that you're afforded a great opportunity, but it also takes great responsibility."

Suh's no stranger to the harsh realities of NFL contracts. He made headlines when he signed a six-year, $114 million deal with the Miami Dolphins in 2015, but that didn't automatically translate to a nine-figure paycheck. When players sign huge contracts, they should really cut that number in half to get a better picture of their earnings, he explains to Business Insider.

And, thanks in part to Buffett, Suh knows that the money he makes from football isn't everything. He's already preparing other streams of income to sustain him whenever he's done playing. "If you want to maintain your same lifestyle, you have to continue to work to bring in that cash flow," he says in the CNBC documentary.

With Buffett's guidance, the player has made investments in real estate, technology and restaurants. And although he's got the Oracle of Omaha advising him, Suh makes a point of remaining hands-on with his money.

"I've always loved numbers, so I like to be involved and understand what's going on, not just [be] a person who always wants to take great advice," he says. "Understanding my investments, understanding how to be sustainable and understanding how I can progress my family to the future is going to be huge."

Suh and Buffett first met in 2009 when Suh was still in college, playing football for the University of Nebraska. A longtime Cornhuskers fan, Buffett asked to meet Suh before a game against rival Oklahoma.

After his brief initial chat with Buffett, a friend encouraged Suh to push for an official meeting with the business legend. "I was like, 'There's no way he wants to sit down with me, I'm just a young kid,'" Suh says.

But Suh's interest in business won out: "He'd be a great resource to have at that helm, and so I said, 'Why not, what do I have to lose?'"

Buffett responded, and the two ended up talking for hours. From then on, Buffett became a mentor to Suh, and the two still keep in touch.